Tadich/Sams/Johns/Alfreds and best breakfast in Union Square
Sears was taken over by a chain a few years back and reports about it are not good.
If this is a weekend Canteen gets good reviews. There was just a good report for Cafe Andree. Dotties True Blue Cafe is a board favoirte.
Depends on what you want out of a restaurant. If you are looking for old SF ambiance and seafood, I'd pick Tadich. If you are looking for a steakhouse then Alfred's is the only real option out of that list.
Also, where are you coming from? If a city known for steak it isn't a strength of SF.
Hope you will report back after your visit on what you chose and if you liked it.
Tadich Grill - Sam's is sooooo much like Tadich that I wouldn't select them both. Perhaps another option - are you staying in the downtown area? There are a bunch of places you could select from that would give you more variety. Maybe Tadich (an oldie) and Bar Crudo (a new-ie). I've not been to Canteen, but it gets great reviews - I think they may only do weekend breakfasts, so you should check it out.